This invention relates to a wheel bearing assembly for supporting a vehicle wheel.
Among vehicle wheel bearing assemblies, there are ones for supporting driving wheels and ones for supporting non-driving wheels. Among both types of wheel bearing assemblies, there are many types.
FIG. 13 shows one example thereof. This wheel bearing assembly is for a driving wheel, and comprises an outer member 1, an inner member 11 and double-row rolling elements 31 mounted between the outer member 1 and the inner member 11.
On the inner periphery of the outer member 1, two raceways 3 are formed while on the outer periphery thereof, a flange 2 for mounting to the vehicle body is provided.
The inner member 11 has a hub ring 12 and a raceway member 13. A wheel-mounting flange 15 is provided on the outer periphery of the hub ring 12 at one end thereof. At the other end, a small-diameter portion 12b is formed on which is fitted the raceway member 13.
On the outer peripheries of the hub ring 12 and the raceway member 13, raceways 16 and 20 are formed, respectively. Between the raceways 16, 20 and the raceways 3 of the outer member 1, the rolling elements 31 are mounted.
In order to impart a pre-load to the rolling elements 31, a spline shaft 14c provided on an outer joint member 14 of a constant-velocity joint is mounted into a spline hole 17 formed in the hub ring 12, and a nut 21 is tightened on a threaded shaft 14d provided at the tip of the spline shaft 14c. 
The wheel bearing assembly is delivered from a wheel bearing manufacturer to an automobile assembling factory of an automotive manufacturer. At the factory, a separately delivered brake rotor 40 is fixed to one side 15a of the wheel-mounting flange 15 of the wheel bearing assembly by tightening bolts 42.
After assembling, if there is a considerable run-out of the braking surfaces 40a of the brake rotor 40, the frictional force will not be constant, so that vibrations and abnormal noise, so-called brake judder are produced during braking.
In order to suppress vibrations and abnormal noise produced due to run-out of the braking surfaces 40a of the brake rotor 40, heretofore, increasing the machining accuracy of parts has been sought. But such a solution is time-consuming and results in higher cost.
Also, since machining errors of parts accumulate in assembling them, even if the machining accuracy of individual parts is increased, it is difficult to suppress run-out of the braking surfaces 40a of the brake rotor 40.
Further, on the brake rotor-mounting surface 15a of the wheel-mounting flange 15 and the surface 40b of the brake rotor 40 that abuts the brake rotor-mounting surface 15a, as shown in an enlarged view of FIG. 14A, there exist undulations. Thus, a combination of such undulations will largely influence the run-out of the brake rotor 40. Heretofore, at an automobile assembling factory, when the wheel-mounting flange 15 of the wheel bearing assembly and the brake rotor 40, which are delivered as separate parts, are assembled, various adjustments including phase-adjustment at positions where run-out of the wheel-mounting flange 15 and run-out of the braking surfaces 40a of the brake rotor 40 are maximum and minimum have been carried out. Such a method is troublesome and poor in workability.
Also, when the brake rotor-mounting surface 15a of the wheel-mounting flange 15 and the surface 40b of the brake rotor 40 are brought into abutment with each other, due to the above said undulations, an air gap is formed therebetween. When the wheel-mounting flange 15 and the brake rotor 40 are pressed against each other in mounting the wheel, as shown by single-dot chain line in an enlarged view of FIG. 14B, the brake rotor 40 is liable to deform due to the air gap.
Such a deformation of the brake rotor 40 increases run-out of the brake rotor 40, thus causing brake judder.
An object of this invention is to suppress deformation of the brake rotor, thereby preventing brake judder in a simple and inexpensive manner.